float.cc

#include <stdio.h>
#include <math.h>
#include <stdint.h>

static float rt(float x) {
    volatile double g = static_cast<double>(x);
    return static_cast<float>(g);
}

int main() {
    for (uint32_t i = 0; i != (uint32_t)-1; ++i) {
        float f = *(reinterpret_cast<float*>(&i));
        float g = rt(f);
        uint32_t o = *(reinterpret_cast<uint32_t*>(&g));
        if (isnan(f) ? !isnan(g) : f != g) {
            fprintf(stderr,
                    "BAD: %08x (%f) -> %08x (%f)\n",
                    i, f, o, g);
        }
        if ((i & 0xffffff) == 0) {
            fprintf(stderr, "%08x...\n", i);
        }
    }
    return 0;
}